Biomedical Engineering Reference
In-Depth Information
Figure 4.20
AFM images acquired in the phosphate-citrate buffer (pH 5.0). The number of layers of all these chitosan-alginate
multilayer films is six. The assembly pH of chitosan of all these multilayer films is 3.0. The assembly pH of alginate
is (a) 3.0, (b) 4.0, and (c) 5.0. The Z range (maximum height) is (a) 30 nm, (b) 100 nm, and (c) 400 nm. (From Yuan, W.
Y. et al. 2007. Langmuir 23: 13046-13052. With permission.)
nanotube wall can be controlled by changing the assembled layers. The nanotubes are
internalized into the HeLa cells and localized in the cell cytoplasm.
Core-shell chitosan-alginate nanoparticles can be formed on liposomes via LBL assem-
bly. Low- M W chitosan favors the creation of smaller chitosan-alginate nanoparticles, as
compared to high- M W chitosan [239]. The mean particle size decreases when chitosan was
absorbed on a previously adsorbed alginate layer. This behavior might be explained by the
ability of the shorter polymer chains of alginate to easily diffuse between the longer poly-
mer chains of chitosan due to the strong ionic electrostatic interactions and complexation
of the polymers forming a denser network. These core-shell assembly nanoparticles not
only possess a high loading capacity that can be altered by the number of polyelectrolyte
layers, but also provide sustained release of the entrapped protein for extended periods of
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